
Clark County Today takes a look back at the likelihood of a major rip of the full Cascadia Subduction Zone that would trigger a magnitude 9.0 earthquake in the next 50 years
John Ley
for Clark County Today
The Great ShakeOut earthquake drill will take place on Thursday (Oct. 17) at 10:17 a.m. This is the time when the first shake is simulated, and participants should drop, cover, and hold on for at least 60 seconds. But locally, what are the odds of a major earthquake?
“Oregon is pretty boring,” says Harold Tobin, director of the PNW Seismic Network. He shared a video highlighting 40 years of earthquakes at the 2019 Pacific Northwest Earthquake Forum. Tobin noted most of the earthquakes have been in California, Washington, or offshore.
The biggest concern is a major rip of the full Cascadia Subduction Zone triggering a magnitude 9.0 earthquake in the range of 10-14 percent in the next 50 years. Put another way, there is an 86 to 90 percent chance an M9 earthquake will NOT happen in the next 50 years.
This is also relevant in the current Interstate Bridge Replacement Program (IBR) discussion for replacing the current two bridge structures. People should know the IRB is NOT designing the replacement bridge to the highest standard, which would best withstand an M9 or greater earthquake. They have previously reported they are not designing it to the 2,500-year standard; but a 500-year standard, which is the most commonly used standard for assessing seismic risk.
Read the following article Clark County Today published three years ago, regarding earthquakes here in the Pacific Northwest, as part of this year’s “Great Shakeout” event.
An additional article is about Oregon’s plans addressing seismic vulnerabilities to their transportation system.
Also read:
- Letter: Gadflies unite!Shauna Walters responds to IBR’s Greg Johnson calling project opponents “gadflies” and urges continued opposition to costly light rail plans.
- Expect morning commute delays on northbound and southbound I-5 in Clark County ThursdayExpect delays on I-5 near Woodland, La Center, and Ridgefield Thursday morning as WSDOT crews conduct rolling slowdowns for tree removal work.
- Opinion: Cut costs on I-5 Bridge replacement projectMargaret Tweet discusses the rising costs of the I-5 Bridge replacement project, highlighting concerns about light rail funding and congestion relief.
- Washington looks to raise $1.6 billion from tolls for new I-5 bridgeWashington lawmakers are planning to raise billions through tolls to fund the new I-5 bridge connecting Washington and Oregon.
- Rep. John Ley issues statement after Marie Gluesenkamp Perez invites the USDOT Secretary to discuss the I-5 Bridge Replacement ProjectRep. John Ley criticizes the I-5 Bridge project, arguing it prioritizes transit over reducing congestion and saving time.